Pistol primers in 32-40

[stubbicatt]

Been experimenting with 32-40. Read elsewhere that pistol primers give better results than do rifle primers in this cartridge. Whether that is because they are easier to detonate or because they have a better mixture of priming compound or what, I am not entirely sure yet.

However, as I understand it, pistol primers are not as tall as rifle primers, so when seated in the primer pocket, they will be seated more deeply than a rifle primer, giving rise to the question in my mind whether a firing pin will be long enough to reach them to set them off.

So I tried a little test. I simply seated a CCI large pistol primer in a 32-40 case, inserted it into the chamber, and dropped the hammer on it.

Bang!

So at least the first step returned a positive result. I also put the muzzle of the rifle into an old blanket/comforter I use to cover up my old motorcycle in the garage in the winter to keep dust off it. I did this to sort of muffle the blast from the little "amorce" when I set it off. I noticed a blackened, muzzle diameter area in the fabric of the blanket. Presumably the pistol primer blast traversed the entire length of the barrel to make that smudge.

This smudge got me thinking about small charges of powder in a comparatively large case, and powder position sensitivity. I haven't conducted any experiments yet on this phenomenon. The internet has plenty of commentary on this phenomenon, but dang, if the primer blast traverses 20+ inches of barrel to leave a burn mark on a blanket, it just doesn't seem like this powder position could be an issue. (???)

Next comes experimentation with breech seating and what seems like tiny charges of IMR 4227 behind a 200 grain bullet, and muzzle up, and muzzle down, shot preparation and firing over the chronograph.

It is good to learn new techniques, with a new setup. Even if the setup is more than 100 years old. It is also good to read of H.M. Pope and the others of that era and their technique and their results. It is interesting to compare these results, using the same equipment as they did then, today.

 

[Reloadron]

The height difference between Large Pistol and Large Rifle primers is about .010 on average. Things look a little like this:



As long as when seated to bottom out the firing pin can still strike the primer with adequate force and depth it will go bang. Apparently it worked for you.

Oh yeah, a primer fired in an empty case will indeed travel the length of the barrel. A Google of "primer brisance" will hopefully get some images of primers detonating. I can't recall where I saw them but some violent little explosions. Years ago I got into the how much powder in the case and how it ignites thing. You can end up goig OCD on that subject.

Ron

 

[Don McDowell]

Pistol primers will work and work well in a number of low pressure rifle cartridges. A good number of bpcr competitors use pistol primers. Most use a thin piece of ashless paper to "headspace" the primer so the primer doesn't peen the face of the breechblock and cause problems with the firing pin. They simply cut the paper in strips and place the strip under the case and seat the primer thru the paper strip.

 

[tightgroup tiger]

I noticed a blackened, muzzle diameter area in the fabric of the blanket. Presumably the pistol primer blast traversed the entire length of the barrel to make that smudge.

Did you try that with a rifle primer? I was never aware that a pistol primer was any hotter than a rifle primer but I may have just learned something today.

 

[Jesse Heywood]

Here is more info about primers than you ever wanted to know.
www.sksboards.com/smf/index.php?topic=56422.msg646510

 

[stubbicatt]

Did you try that with a rifle primer? I was never aware that a pistol primer was any hotter than a rifle primer but I may have just learned something today.

I did try a rifle primer into the same blanket, but with a different cartridge, 45-70 and would be loath to try to compare the two burn marks on the blanket. Mostly I do this with a new acquisition to make sure it goes "bang" before proceeding to load up any ammo, and later finding I have a firing pin issue.